Biology subjects

Sevegnani, M.

Publications and source records attributed to Sevegnani, M..

3 recordsLinked to original sources

bioRxiv2023

Parkin R274W mutation affects muscle physiology via the PARIS-PGC-1α pathway

Recessive mutations in the Parkin gene (PRKN) are the most common cause of young-onset inherited parkinsonism. Parkin is a multifunctional E3 ubiquitin ligase that plays a variety of roles in the cell including the degradation of proteins and the maintenance of mitochondrial homeostasis, integrity, and biogenesis via the PARIS-PGC-1 pathway. In 2001 the R275W mutation in the PRKN gene was identified in two unrelated families with a multigenerational history of postural tremor, dystonia and parkinsonism. Drosophila models of Parkin R275W showed selective and progressive degeneration of dopaminergic neuronal clusters, mitochondrial abnormalities, and prominent climbing defects. In the Prkn mouse orthologue, the amino acid R274 corresponds to human R275. Here we described a muscle phenotype in R274W +/+ mice and discovered that a defective Parkin-PARIS-PGC-1 pathway may impact mitochondrial biogenesis and, eventually, myoblast proliferation and differentiation.

animal behavior and cognition↗

bioRxiv2023

Dopamine neuron dysfunction and loss in the PrknR275W mouse model of Juvenile Parkinsonism

Mutations in the PRKN gene encoding the protein PARKIN cause Autosomal Recessive Juvenile Parkinsonism (ARJP). Harnessing this mutation to create an early-onset Parkinsons disease (PD) mouse model would provide a unique opportunity to clarify the mechanisms involved in the neurodegenerative process and lay the groundwork for the development of neuroprotective strategies. We created a knock-in mouse carrying the homozygous PrknR275W mutation, which is the missense mutation with the highest allelic frequency in PRKN patients. In PrknR275W mice, we analysed the anatomical and functional integrity of the nigrostriatal pathway, including striatal DA content and evoked striatal dopamine (DA) release, as well as the motor phenotype. We report here that PrknR275W mice show early DA neuron dysfunction, age-dependent loss of DA neurons in the substantia nigra, decreased DA content and stimulus-evoked DA release in the striatum, and progressive motor impairment. Together, these data show that the PrknR275W mouse recapitulates key features of ARJP. Thus, these studies fill a critical need in the field by introducing a promising new PD model in which to study causative mechanisms of the disease, as well as test therapeutic strategies.

neuroscience↗

bioRxiv2022

LRRK2 regulates dendritic spine dynamics through interaction with post-synaptic actin cytoskeleton

Parkinsons disease (PD) is a multisystemic disorder that manifests through motor and non-motor symptoms. Motor dysfunction is the most debilitating and it is caused by the degeneration of dopamine-producing neurons in the substantia nigra pars compacta (SNpc). Increasing evidence suggests that synapse dysfunction precedes neuronal loss by years. Still, early synaptic alterations in PD remain poorly understood. Here we integrate literature meta-analysis, proteomics and phosphoproteomics with biochemical, imaging and electrophysiological measurements in neurons and brains from knockout and knockin Lrrk2 mouse models, as well as human iPSC-derived neurons lacking LRRK2. We demonstrate that phosphorylation of LRRK2 at Ser935 and of RAB proteins is induced by brain-derived neurotrophic factor (BDNF) stimulation in differentiated SH-SY5Y cells and primary mouse neurons. Affinity-purification coupled with mass spectrometry (AP-MS/MS) revealed a significant remodelling of the LRRK2 interactome following BDNF treatment, with enhanced association of LRRK2 to a network of actin cytoskeleton-related proteins. Gene-ontology analyses of both literature-curated LRRK2 interactors and phospho-proteome from striatal tissues with elevated LRRK2 activity (G2019S knockin mice) highlight synapse-actin remodelling as major affected pathways. We further observed that loss of LRRK2 impairs BDNF signaling and alters postsynaptic density architecture. One month-old Lrrk2 knockout mice display structural alterations in dendritic protrusions, a phenotype that normalizes with age. In human iPSC-derived neurons, BDNF enhances the frequency of miniature excitatory post-synaptic currents (mEPSC) in wild-type cells, an effect that is abolished in the absence of LRRK2. Taken together, our study discloses a critical role of LRRK2 in BDNF-dependent synaptic modulation and identifies the synaptic actin cytoskeleton as a convergent site of LRRK2-associated pathophysiological processes in PD.

neuroscience↗